Fighting Algae / Prevention

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Jwohleber

Member
Mar 19, 2020
13
Houston, TX
Hello I'm new to TFP, but I've found the site very helpful in troubleshooting my pool so far. Before I found this site I was using tablets and had high CYA levels. I've since drained water from the pool and corrected that issue. My issue now is trying to fight green algae. I completed a successful SLAM about a 10 days ago. But algae returned within a week even with maintaining proper chemistry levels (checked at least daily), we did have some rain though.

I'm trying to determine how practical it will be to keep algae from growing in my pool. I was hoping that after killing the algae, vacuuming the dead algae out, backwashing then rinsing the filter, I would be able to keep it from returning by just maintaining proper levels. I'm assuming algae spores can be introduce easily back into the pool (leaves, pollen from trees, etc.). Should proper chemistry levels keep new algae from blooming or is keeping algae spores out in the first place the only way to keep algae at bay?

The algae isn't bad, it just accumulates on the walls over a few days. Most will come off with brushing. I'm currently SLAMing again. I was trying to search for algae sources around the pool to make sure I eliminated all the algae I could. I have a travertine pool deck, and my skimmers are covered with tiles instead of the plastic covers. I noticed yesterday there was some algae growing under the travertine tile I remove to access the skimmer. It wasn't in the pool, but I could easily see it spreading spores into my pool water from there. I cleaned that up, but it got me thinking about the waterline tile grout lines. I get algae growing in the grout lines just above the water line (nothing excessive maybe a few grout lines out of the 100 or so grout lines in the pool). I can clean these up too, but I'm not sure it's practical for me to keep anything from ever growing in these spots (being in and out of the water makes it a good spot for growth).

Levels:
OCLT: Last night <1ppm
FC: 16 CC: 0
PH: 7.2 at start of SLAM (plaster is 1 year old, and PH likes to drift higher to 7.6-7.8, lowered PH before starting SLAM)
ALK: 95
CYA: 30
CH: 200
(from pool store test a week or two ago)
Iron: 0.1ppm
Cooper: 0.3ppm (not sure if this is from the Maxblue tablets I was previously using or pool fill water, city water)
 
Welcome to the forum :wave:

I'm trying to determine how practical it will be to keep algae from growing in my pool. I was hoping that after killing the algae, vacuuming the dead algae out, backwashing then rinsing the filter, I would be able to keep it from returning by just maintaining proper levels.
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That's EXACTLY how it works. So for now, please continue the SLAM.

Are those your test results or the pool stores (disregarding the iron and copper) ?

Let's discuss how you finish a SLAM but tell us if they are your tests first.
 
Those are all my test results with the exception of the metals.

Should I be seeing any algae accumulation during the SLAM process at all? For example, I brush all the algae off at the beginning of the SLAM, but there is a little accumulation on the walls the next afternoon. I'm keeping the pump running continuously.
 
I'm checking in the morning before work, then in the afternoon and then in the evening. I've been trying to keep FC a little higher in the morning, so it's not under the SLAM levels in the afternoon. This morning I bumped it up to 16 from around 14 to try to keep it elevated until this afternoon. I normally add chlorine in the morning and afternoon.

I think I called the TA 95 because I was doing the 25mL test and multiplying my drop count by 10. I wasn't quite sure if the color was already changed by drop 9 or if it wasn't truly changed until drop 10, so I split the difference.
 
Anytime algae appears on your walls, brush ALL the pool walls.....get that algae out into the SLAM chlorinated water and let it be killed.

Brushing and vacuuming almost daily are an important part of the SLAM process
I wasn't quite sure if the color was already changed by drop 9 or if it wasn't truly changed until drop 10, so I split the difference.
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All drops based testing is ended when the very last drop you make results in NO FURTHER COLOR CHANGE. Subtract that drop that made no difference and that is the end of your test. So, in your case above, you would've added an 11th drop and probably saw it made NO CHANGE......your TA is 100.
 
Jwohleber said:
So some algae reforming on the walls during a SLAM isn't unusual?
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That shouldn't happen. The first brush should loosen up any visible stuff and cloud the water. The chlorine will kill it, hence the water going grayish from green. But algae can be tenacious stuff and arms get tired, so you should start in a different spot everyday. Algae develops a slimy protective film, almost like scab, to seal it up against chlorine. Brushing scrapes it off.

Don't neglect other hiding places. like inside and beneath ladders and steps or behind lights. Check out the pictures

Think I may have found my FC demand issue?

Not saying conclusively BUT.... I've been chasing a FC demand issue that maintaining shock levels for days wasn't taming. Have been losing about 6ppm FC per night while trying to achieve the OCLT. Pool is sparkling as if there is almost no water in it. No CC or less than .5. Still consuming...
www.troublefreepool.com www.troublefreepool.com

Water problems

I've been slamming my pool for about a week now and although I have cleared the water up my water is still cloudy. Cya is at 40 so I'm using 16 as my chlorine shock level according to the cya/chlorine chart. When I started slamming I had a combined chlorine of 1 and I did get that down to 0. Any...
www.troublefreepool.com www.troublefreepool.com

Problem Found and Ideas needed

I began SLAMing my pool 4 days ago (84 hours). My CYA is somewhere between 25-40 so I used the SLAM values for Mustard at 30-40 CYA, which is about FC 22 or mustard and 14 for a normal SLAM. I checked the FC every 3-4 hours and after the first couple of checks where the FC drop was 5-8 the...
www.troublefreepool.com www.troublefreepool.com

DARN Ladder!! Algae Culprit

Pardon my French, but this ladder we have has, I believe, kept us from ever getting rid of algae, regardless of the SLAMs or scrubbing we do. Here are some photos of all the nooks and crannies. How do I clean this sucker?! I have poured bleach in each hole and scrubbed with a bottle scrubber...
www.troublefreepool.com www.troublefreepool.com

Once the algae is completely eradicated, maintaining adequate FC for your CYA level will keep it from taking hold again. Brushing is an important part because some areas of the pool may have poor circulation and brushing ensures that all areas stay chlorinated.
 

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It's possible you had some hidden algae in a niche/ladder/etc. last time that didn't get cleared out, or that you stopped it a bit too early. Better to keep the SLAM levels an extra day or two than to have the algae come back. :)

If you do have algae growing DURING a SLAM then something is off. Maybe recheck the CYA and see if the 30 was too low?
 
Well I did find some algae growing on the tile that covers one of my pool skimmers. I cleaned that up, but i haven't checked all the grout lines for the water line tiles yet. I brush the tiles when I brush the pool, but there could be small amounts there. That's what got me thinking it's seems rather challenging to keep anything from growing in those spots. Some algae growth seems inevitable in those damp areas that aren't exposed to chlorine often. Is that going to cause problems if I brush a couple of times a week?

I'm hoping the pool chemicals will be able to fight off those small amount of algae in the future without needing to reSLAM all the time. The way the SLAM process is described though, it seems like you really need to be through in eliminating all traces of algae so it doesn't come back. Which is making me worry that trace amounts of algae getting reintroduced can get you right back to where you started even if your chemistry is good. In a humid climate like Houston, algae seems to have no problem finding a spot to start growing. Hopefully that's not the case, so I'm looking for tips in my prevention strategy.

Thanks
 
Jwohleber said:
Well I did find some algae growing on the tile that covers one of my pool skimmers. I cleaned that up, but i haven't checked all the grout lines for the water line tiles yet. I brush the tiles when I brush the pool, but there could be small amounts there. That's what got me thinking it's seems rather challenging to keep anything from growing in those spots. Some algae growth seems inevitable in those damp areas that aren't exposed to chlorine often. Is that going to cause problems if I brush a couple of times a week?

I'm hoping the pool chemicals will be able to fight off those small amount of algae in the future without needing to reSLAM all the time. The way the SLAM process is described though, it seems like you really need to be through in eliminating all traces of algae so it doesn't come back. Which is making me worry that trace amounts of algae getting reintroduced can get you right back to where you started even if your chemistry is good. In a humid climate like Houston, algae seems to have no problem finding a spot to start growing. Hopefully that's not the case, so I'm looking for tips in my prevention strategy.

Thanks
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There's nothing special about Houston. There's always that little strip that isn't submerged but sometimes gets wet just from ripples. A bunch of people get in, the level rises and it's submerged in chlorinated water. You come by with the brush along the water line tile maybe once a week and it'll be fine.
 
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Still fighting with algae coming back after a couple of weeks. Even with keeping pool chemistry within the recommend ranges.

I'm wondering if my pool heater could be helping algae form. I have a bypass for the heater with a check valve on the downstream side to prevent backflow. I had been keeping the heater bypassed just because I wasn't using it and it adds a couple lbs of pressure to the system. Could algae grow in the heater with the water being stagnate? There's no sunlight or source of oxygen in that loop though. For now I'm planning on keeping the bypass valve at the halfway point, so water can flow either around or through the heater. I'm sure most of the water will flow around the heater, but some water will also sweep through the heater.

Just curious what others experiences are with heaters being bypassed. Thanks
 
I know it was mentioned before but I thought I’d post this anyway.

I have been brushing my pool and loosening up anything that the walls on the walls although it really wasn’t.

however on a whim I happen to just pull out the ladder. I had brushed under it with the brush by hand and a lot of dirt and slimy gunk had come out. Since I had nothing better to do I decided just to pull the ladder out and clean it that way since I could easily see what was left to clean.

well when I turned that ladder upside down I couldn’t believe the amount of slimy gunk and I’m assuming algae that we’re still there.

I didn’t even bother brushing. Instead I made sure the ladder was upside down and then I poured liquid bleach on each of the steps and then let it sit overnight and let the bleach do it work. When I came out the next day all of that was gone! It literally disintegrated away and I didn’t have to brush.

i’m convinced that was part of the reason that it was taking so long to SLAM.

if you haven’t done that try and see what turns up.
 
When I started the SLAM my levels were as follows:
PH 7.5
ALK 70
FC 15
CYA 30

I checked the FC yesterday late morning and it was 12, so I added 16oz of 73% Cal-Hypo. I also noticed the check valve downstream of my heater wasn't open much at all, I adjusted the valve upstream to pinch back a little more on the bypass line. Now the flapper in the check is open at least a 1/3 so I know water is flowing. I checked the FC in the evening and it was back down to 11 so I added a gal of 10% bleach in the evening. It was pretty cloudy yesterday, so I was surprised to see that much of a drop after only 6-8 hours. This morning the FC was 12 and CC was 0. I added 16 oz of 73% cal-hypo and I'll check things again this afternoon/evening.

I was able to pass the OCLT test last time after one day (with the heater bypassed). This time I am using up chlorine overnight, so hopefully the heater is the culprit. Is that possible with no sunlight/oxygen? Anyway I'll keep SLAMing away and see where that gets me.
 
Checked FC yesterday afternoon. The reading was down to 7, so I added 32 oz of cal-hypo. I checked FC in the evening and it was still up at 13. I vacuumed out the pool last night. This morning I checked the FC at it was still at 13, so hopefully I've got everything cleared out.

As a side question, I've got another basic test kit that using a chlorine neutralizer before testing for PH. Is it possible to get an accurate reading for PH using that style of test during a SLAM? I'm not sure of the chemistry involved with the PH reagents.
 

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